Studies were undertaken this past year to extend our initial investigations utilizing lectins as serological reagents to examine the surface carbohydrates of lymphocytes. We find that two lectins capable of binding oligosaccharides with nonreducing terminal D-galactosyl and N-acetyl-Dgalactosaminyl residues react with only a portion of murine splenocytes isolated from a single animal. Immunofluorometric analysis of the binding of Wistaria floribunda agglutinin (WFA) to murine splenocytes demonstrates that 44% of the cells are unable to react with this lectin. Preparative agglutination of the cells followed by density separation of single from agglutinated cells results in isolation of two distinct populations. Following repeated washing of the fractionated cells with lactose, an inhibitor of the lectin, 80% of the nonagglutinable cells are negative and 90% of the agglutinable cells are reactive with WFA. Interestingly, although 46% of the original splenocyte population exhibits surface immunoglobulin (sig), 96% of the nonagglutinable cells are sig negative. Fractionation of splenocytes by Sophora japonica lectin results in isolated subpopulations which are distinct from those fractionated by WFA. We have also employed a polyacrylamide gel electrophoretic technique to obtain fluoresceinderivatized glycopeptides which allow us to explore the binding specificity of an antiglycan antibody which may be of use to study the structure of the carbohydrate moieties of glycoconjugates. Additional studies have focused on the carbohydrate moieties of secreted lymphocyte products. Factors influencing the structure of the carbohydrate moieties of glycoproteins may be better understood by comparing the structure of the glycan units of myeloma proteins expressed by related cell lines. We have employed our PAGE procedure to examine the structure of the carbohydrate moiety of glycopeptides derived from myeloma proteins produced by two related myeloma cell lines. To date, only preliminary structures have been deduced and further research along these lines is required to obtain the complete structures of these lymphocyte glycoconjugates.